The focus of the proposed program is a study which will lead to the utilization of natural biological material or synthetic substitutes to improve human health and well being. The investigations encompass both fundamental mechanisms, and functional modes, in complex corporal and extra-corporal systems. In view of the complexity of these goals the program project is multi-disciplinary and involves professional personnel whose main professional interests lie in the biological, medical, and physical sciences, and in engineering. Projects of the program are arranged in five categories. The first category deals with the characterization and development of surfaces which can remain in contact with static or flowing blood for long periods without alteration of blood composition or thrombus formation. The second category deals with the structures of natural and synthetic membranes, and with their dynamic behavior. In a third category are placed projects associated with the measurement of mechanical stresses in connective tissue and their relationships to long term joint function. The fourth category deals with transport in the vascular system; with the control mechanisms regulating the distribution of blood flow in organ systems, with blood flow itself, with the transport of chemical species to bounding surfaces, and with the control of cardiac function. A fifth category is comprised of projects which entail the development of novel instrumental methods especially suited to the study of biological materials, and particularly those of interest in the program project.